Posted by BillS on March 04, 2013 at 14:03:55:
In Reply to: PFAUTER P900 DEFFERENTIAL CHANGE GEARS posted by chuck tucker on March 04, 2013 at 10:41:02:
According to the "Gear FAQ" here, the P900 could be either dial feed (hydraulic) or uses feed change gears.
If you are using CPC-HOB, the machine would be entered as type "A".
Assuming your hob is single lead, then:
gearing ratio = 0.3598808
If you don't use CPC-HOB, then you need to find a gear set that has a ratio close to the number above (as close as possible).
The FAQ topic:
Hob machine Constants and Types
will show you differential constants for different machines, and at the end of that table is a description of formulas. Your formula is based on a type "A" machine.
Based on using Diametral Pitch (DP), The constant part of the formula is:
(225/8)
C = ------------- = 0.352459273
(25.4 x PI)
So your complete formula would be:
0.352459273 x SIN(Helix Angle) x DP
Gear Ratio = ----------------------------------------------- = 0.3598808
Hob Starts
There is no "absolute single gearset" for this ratio, but rather you will need a "best gearset"
based on your change gear inventory and machine mounting conditions
(swing arm, CC shafts, change gear pitch, etc).